1. Field of the Invention
The present invention relates to a fuel cell stacking body formed by stacking fuel cells that have an electrode assembly and separators that sandwich the electrode assembly, and in which the separators are provided with voltage measuring sections that enable a voltage to be measured.
2. Description of the Related Art
In recent years, fuel cells have attracted attention as a new power source for vehicles and the like. Generally, a fuel cell is formed by sandwiching between separators a membrane electrode assembly (MEA) that is formed by disposing gas diffusion electrode layers on either side of a solid polymer electrolyte membrane. In order to generate power using this type of fuel cell, an electrochemical reaction is generated by supplying gas fuel (for example, oxygen gas) to one gas diffusion electrode layer of the fuel cell, and supplying oxidizer gas (for example, air that contains oxygen) to the other gas diffusion electrode layer. Because, basically, the only by-product of this power generation is harmless water, this type of fuel cell is receiving attention because of both its benefits to the environment and its utilization efficiency.
Using a single fuel cell it is difficult to obtain sufficient power to drive a vehicle. Therefore, investigations are being carried out on the forming of a fuel cell stacking body by stacking a plurality of fuel cells, and then mounting this fuel cell stacking body in a vehicle in order to obtain sufficient power to drive the vehicle.
In this case, in order to monitor whether or not each of the fuel cells forming the fuel cell stacking body is generating power normally, it is extremely important that the voltage of the fuel cells be detected. Conventionally, as is shown in FIG. 10, protrusion shaped and groove shaped voltage measurement terminals 2 are provided on the separators of the fuel cell stacking body 1. By connecting the voltage measurement terminals 2 to connectors connected to a voltage measuring apparatus (not shown), the voltage of the separators on which the terminals are provided is measured, thereby enabling the voltage of each fuel cell to be detected.
However, the following problems arise in the conventional fuel cell. Namely, conventionally, the voltage measurement terminals 2 of each fuel cell are typically placed in series in the same position with respect to the stacking direction (see FIG. 10). Therefore, if connectors for connecting to the voltage measuring apparatus are provided separately for each voltage measurement terminal 2, the concern arises that the wiring connecting the connectors with the voltage measurement apparatus will become tangled up when the respective terminals 2 are connected to the connectors. In addition, because it is necessary to connect a connector to each one of the terminals 2, the task of making the connections is extremely onerous.
Accordingly, the use of a connector 4 obtained by forming a plurality of connectors 3 in the shape of a unit (i.e., a connector unit) so as to enable a plurality of terminals 2 to be connected in a single group is being examined. However, it is desired that the thickness of each fuel cell be made as thin as possible in order for the fuel cell stacking body 1 to be mounted in a vehicle, and this has inevitably resulted in a trend towards the spacing W between terminals being made as narrow as possible. Therefore, as is shown in the side cross-sectional view in FIG. 11, when the terminals 2 are arranged in series, if the spacing W between terminals 2 is narrow, the concern arises that the thickness X at the end portion side of the connector unit 4 will not be able to be secured sufficiently, resulting in the strength being insufficient. In addition, the concern also arises that the spacing Y between connector units 4 will not be able to be secured sufficiently, resulting in the connector units 4 knocking against each other and causing the connections to be blocked.
The present invention was conceived in view of the above circumstances, and it is an aim thereof to provide a fuel cell stacking body that makes possible the use of a connector (connector unit) that can be connected to a plurality of voltage measurement portions at the same time, even when the thickness of the fuel cells is made thin.